1. Field of the Invention
This invention generally relates to wireless communications, for example, cellular communications.
2. Description of the Related Art
The use of wireless communications is rapidly growing. Wireless communications devices such as cellular phones and wireless personal digital assistants (“PDA”) are ubiquitous in today's culture. These devices transmit and/or receive audio and/or data wirelessly. For example, cellular phones may transmit and receive audio, text messaging, and may even allow access to the Internet. PDAs typically transmit and/or receive electronic mail (“e-mail”) and may provide access to the Worldwide Web (“WWW”). These wireless communications devices are typically handheld battery powered devices which a user operates using keyed entries, stylus strokes, and/or voice activation by way of a user interface (“UI”). Many wireless communications devices also include a display for displaying information and/or a command menu which forms part of the UI. Wireless communications devices also typically include an antenna, a transceiver or a transmitter and receiver, and a processor such as a microprocessor, application specific integrated circuit (“ASIC”) and/or digital signal processor (“DSP”) for controlling operation.
The wireless communications devices rely on wireless communications service providers for providing subscribed services. The wireless communications service providers operate wireless communications service provider systems that provide for registration, authentication, location updating, handovers, and call routing. The wireless communications service provider systems typically employ a Home Location Register (“HLR”) and a Visitor Location Register (“VLR”) to provide call routing and roaming. The HLR contains all of the administrative information for each subscriber registered with the wireless communications service provider, along with current location information for a wireless communications device currently associated with the subscriber. The VLR contains selected administrative information from the HLR which is required for call control and for providing subscribed services for each wireless communications device currently within a geographical area service by the VLR.
Many wireless communications devices include computer-readable media commonly referred to as a subscriber identity module (“SIM”) that contains subscriber related data or information. While the SIM typically takes the form of a physically removable device such as a “smartcard” or similar article, in certain embodiments the SIM may be permanently fixed in the wireless communications device. The SIM typically includes a microchip having a microprocessor and persistent memory such as erasable programmable read-only memory (“EPROM”). In addition to other information, the SIM may store one or more identifiers that uniquely identify a subscriber. Thus, a wireless communications device may be associated or configured with a subscriber's specific identity and related information by physically placing the appropriate SIM into a SIM slot of the wireless communication device.
While other wireless protocols exist (i.e., TDMA, CDMA), one of the most popular of the numerous wireless protocols is the European Global System for Mobile Communications (“GSM”) standard. Under GSM, the SIM stores an identifier commonly known as an International Mobile Subscriber Identity (“IMSI”). The IMSI is hardcoded in the SIM and is protected against change or tampering. The HLR logically relates the IMSI to the telephone number (i.e., Mobile Subscriber ISDN) associated with the subscriber, as well as relating the IMSI to the services subscribed to by the subscriber. Also under GSM, the SIM stores a second identifier in the form of a secret key for subscriber authentication and/or communications encryption, as discussed below. The SIM may be protected against unauthorized use by way of a password and/or personal identity number.
Under GSM, a separate identifier, commonly known as an International Mobile Equipment Identity (“IMEI”), is hardwired or hardcoded into the wireless communications device, and is used to uniquely identify the wireless communications device. The IMSI and IMEI are independent, providing personal mobility by allowing a subscriber to use a SIM in a variety of different wireless communications devices at different times.
In use, the wireless communications service provider authenticates the subscriber at a start of each call, and also authenticates the subscriber at intervals during the call. The wireless communications service provider system typically relies on the Signaling System Number 7 (“SS7”) for signaling between the various functional entities, such as challenging the wireless communications device with a request for authorization. As discussed above, each subscriber is assigned an IMSI and a secret key. One copy of the secret key resides on the SIM and another copy of the secret key resides with the wireless communications service provider in an Authentication Center (“AuC”). During authentication, the AuC challenges the wireless communications device by generating and transmitting a random number to the wireless communications device as part of an authentication request. The AuC and the wireless communications device each generate a respective response, commonly referred to as a “signed response” (“SRES”) based on the secret key and random number using a ciphering algorithm, commonly referred to as “A3”. The wireless communications device transmits the SRES back to the AuC, which authenticates the subscriber if the SRES generated by the wireless communications device matches the SRES generated by the AuC. The wireless communications device and AuC may also generate a ciphering key for encrypting communications based on the random number and secret key using a second ciphering algorithm, commonly referred to as “A8”.
The wireless communications service provider also verifies a status of the wireless communications device, for example, at a start of each call. The wireless communications service provider maintains an Equipment Identity Register (EIR) which stores a list of all IMEIs on the service provider's network and a status for each corresponding wireless communications device. Typically, the EIR will employ three levels of status, a “white-list” status indicating that the wireless communications device is approved to be connected, a “gray-list” status indicating that the wireless communications device may be connected but that problems may exist, and a “black-list” status indicating that the wireless communications device may not be connected due to a problem, for example, where the device has been reported stolen or is not of an approved type for use with the wireless communications service provider system.
The SIM may also store additional subscriber related information such as subscriber configuration or customization information, for custom configuring the wireless communications device to the subscriber's specific requirements or preferences. For example, the subscriber configuration information may identify a home service area, a list of frequently called numbers, voice recognition samples, a list of most recent calls received and/or placed by the subscriber, a notification setting (e.g., ring or vibrate), a list of short messages, etc.
Thus, wireless communication devices typically utilizes subscriber identification information such as an IMSI and/or secret key, as well as subscriber configuration information. The subscriber identification information is hardwired into a chip or card in order to prevent tampering, while the subscriber configuration information is typically soft coded to allow updating. While the SIM may be replaceable in some wireless communications devices, replacement typically requires the wireless communications device and the replacement SIM to be in the same physical location.
Wireless communications systems and devices may require testing to assure performance. One method of testing is to physically transit portions of the area covered by the wireless communications system while operating a wireless communications device. Another approach suggested in U.S. Pat. Nos. 5,875,398 and 6,230,006 and employs remotely operated test platforms which are pre-positioned at a variety of locations in the wireless communications coverage area. The remote test platforms typically include two or more wireless communications devices which may be controlled by a local or central controller to place and receive calls in selected coverage areas.